nickings

Nickings are the fine coal fragments and dust generated when a shearer or pick cuts into the coalface along its side or edge. During the working of a seam, the cutting tool creates a kerf (the narrow slot made by the blade), and the material that spalls, fractures, or crumbles from the sides of this kerf is collected as nickings. They are distinct from the main run of coal because they result from the sideways action of the tool rather than the primary breakage of the face.

The size and character of nickings depend on the coal's friability and the cutting method. A sharp shearer or pick will produce finer material; a dull tool generates larger, more irregular fragments. In practice, nickings range from dust to pieces around 10-15 mm, though this varies with seam hardness and moisture content. They are often mixed with coal dust from the main extraction, so separating them on the basis of origin alone is difficult underground.

Collection and Handling

Nickings fall or are pushed to the side of the working area and are typically gathered into the main coal stream heading toward the conveyor system. Because they are small and dusty, they contribute to both fugitive dust at the face and to the coal's washability downstream. Coarser nickings can be reprocessed or sorted; finer material may be lost as dust or require dedusting before sale.

The term reflects mining's precise vocabulary for describing waste and byproducts. Nickings are not coal dust (which is airborne particles), not slack (the official commercial grade below a size limit), and not stone (roof or floor material accidentally extracted). They occupy a specific moment in the production chain: the immediate debris of the cutting action itself.